Attachment plug cap



March 19, 1935. 'G.-W. LIEBERUM- ATTACHMENT PLUG CAP Filed Feb. 24.1950- Inventor: George W Liebebum.

His AbtOYn- Q Patented Mar. 19, 1935 PATENT OFFICE ATTACHMENT PLUG CAPGeorge W. Lieberum, Stratford, Conn., assignor to General ElectricCompany, a corporation of New York Application February 24, 1930, SerialNo. 430,697

4 Claims.

The present invention relates to detachable caps for attachment plugs,and has for its object the provision of an improved form of cap. Myinvention is specifically directed to an improved means for securing thecontact elements to the cap without the use of screws or equivalentdevices.

For a consideration of what I believe to be novel and my invention,attention is directed to the accompanying description and the claimsappended thereto.

In the drawing which is illustrative of my invention, Fig. 1 is aperspective view of a cap; Fig. 2 is an exploded bottom plan view of thecap and contact elements; Fig. 3 is a view of the cap partly in section;and Fig. 4 is a perspective view of one of the contact elements.

The cap or body 5 may be of any suitable contour. As shown it iscup-shaped having a well rounded upper part 6 and a cylindrical lowerpart '7. In the center is an opening 8 to receive the circuit wireswhich are attached to the contact elements. The body is cut away on itsunder side to form a cavity 9, the peripheral wall of which is definedby the part 7. The bottom wall of the cavity is flat or has flat areasperpendicular to the axis of the body to form seats 10 for the contactelements of which there are two arranged in parallel relation.

- In the bottom wall of the cavity are relatively deep and narrowrecesses 11 one for each contact element. As these recesses do notextend through the cap the metal parts contained therein are fullyinsulated. 12 indicates shallow holes 3 to receive the inner ends of thewire binding compression pressure without cracking and capable ofwithstanding ordinary usage without injury. There are various moldablecompositions available for this purpose.

Both contact elements are alike, each being punched from brass orequivalent material. Each contact comprises a base 14 of considerablearea which rests on a seat 10 and is provided-with an extension 15 toreceive a circuit ire and a binding screw, 13. Extending at right anglesto the base is a contact blade 16. Formed integral with the base andextending in the opposite direction from the blade are two prongs 1'7,said prongs being arranged to enter a recess 11 in the body of the cap.These prongs are of such dimensions that when inserted in place theywill make a snug fit with the walls of the recess, particularly thoseportions of the walls at the ends of the recesses. The edges of theprongs may be roughened or serrated to improve the anchoring means. Inorder to secure the prongs of each element in a recess a wedge 18 isdriven in between the prongs after the contact element has beenassembled in place.

This wedge spreads the prongs by a slight amount and forces the outeredges into firm contact with the walls of the recess. It is advantageousto have the space between the ends of the prongs a little ,greater thanthe space between them at' the point-of connection to the base 14, sothat when the wedge 18 is forced into place it will be retained by theprongs themselves. .*In other words, the space between the prongs formsa dovetail which is slightly greater in width at the inner ends of theprongs than at the outer ends. The wedge 18 may be made of any suitablematerial which can readily be expanded or calked into place. Forexample, I may use lead in the form of an ordinary round shot. Whensuitable pressure is applied to the lead it will be deformed and pressor wedge the inner ends of the prongs apart and largely or wholly fillthe space in the recess which is not occupied by the prongs. As will beobserved, the recesses 11 are substantially rectangular in shape andeach has an enlarged central portion, the purpose of which is to permitof the use of a wedge of substantial proportions and one which isconsiderably thicker than the prongs. Such an arrangement also providesa relatively'large surface contact area between the metal of the wedgeand the surrounding surface of the cap. In assembling, the prongs of thecontact elements are forced into the recess by one operation andsubsequently the wedges are inserted and expanded.

My improved construction has the advantage that it obviates the use ofsmall parts such as metal inserts molded into the body of the cap andalso of screws, which parts are liable to work loose during ordinary useof the cap. Owing to the absence of molded'inserts and screws thereresults a saving in the cost of masufacture, especially of the body andthe cap, and also a saving in the cost of assembly.

What I claim as new and desire to secure by Letters Patent of the UnitedStates, is:-

1. In an attachment plug cap, the combination of a cup-shaped body ofinsulation which has a central opening for circuit wires, flat surfacedseats on opposite sides of the opening and recesses formed adjacent theseats, and a pair of parallel contact elements mounted on the seats,each of said elements having a pair of spaced prongs both of which entera single recess and a metal wedge located between the prongs whichforces their outer edges into firm engagement with opposed walls of saidrecess.

2. An attachment plugcap comprising a body of molded insulation havingpreformed recesses, a flat seat, and a wire receiving opening, contactelements mounted on the seat, each of said contacts having a dividedprong extending into a recess, the distance between the inner ends ofthe parts of the prong being greater than at their outer ends, and awedge that fills the space between the parts of the prong and alsoforces the outer edges of the prongs into engagement with the end wallsof the recess.

3. An attachment plug cap comprising a body of molded insulation havingsubstantially oblong recesses with straight side walls, each or saidrecesses having an enlargement in the center, a flat seat and a wirereceiving opening, contact elements mounted on the seat, each of saidelements having a base supported by the seat, a divided prong thatextends into a recess, and a soft metal wedge that spreads the parts ofthe prong and also fills said enlargement.

4. In an attachment plug cap, the combination of a body of moldedinsulation having a preformed recess and a transverse flat seat, acontact element supported on said seat, said element having a pair ofnarrow prongs extending perpendicularly to the base, both of which enterthe recess and are located side by side therein, and a wedge alsolocated in the recess between the prongs which forces the prongs awayfrom each other into firm contact with the walls of 20 the recess.

GEORGE .W. LIEBERUM.

